A pump action shotgun is a
shotgun with a
magazine, usually a
tube under the
barrel. Between each
shot, the
shooter must move the
foregrip backwards (to eject the empty shell from the chamber) and forwards (to insert a
shell into the gun's
chamber and close the
bolt) -- the
operator pumps the
mechanism, thus the name
pump action.
The magazine usually holds 3 - 5 shells, but most shotgun makers also sell extension kits so you can load more shells into the magazine. Many countries don't allow shotguns capable of carrying more than 2 shells in the magazine, so one has to insert a blank or filler shell into the magazine so that no more than 2 shells can be inserted.
The pump action shotgun is a durable construction which eats heavy loads and takes a beating.
The sound produced by pumping the foregrip should make any intruder wet their pants.
One of the the most famous pump action shotguns might be the Remington 870 Express.